I wonder if anyone can comment if they have experience running minio at scale. It would be a pleasant surprise if a “simple” minio cluster could handle such workload

Does it scale that far?

Likely not that "gracefully". But Ceph absolutely does, and has an S3 gateway.

Using Ceph like S3 could be a bit tricky if all of that 10pb is very small files.

Redhat did an interesting series of blog posts about Ceph and getting it to 1 billion objects

https://www.redhat.com/en/blog/scaling-ceph-billion-objects-...